Viscosimeter



May 25, 1954 G. CARPENTER 2,679,157

VISCOSIMETER Filed Oct. 3, 1949 SYNCHRONOUS MOTOR SPEED A4 INVENTOR. P. G. CARPENTER ATTORNEYS 1, Patented May 25, 1954 VISCOSIMETER Paul G. Carpenter, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Application October 3, 1949, Serial No. 119,256

This invention relates to apparatus for determining the viscosity of a fluid.

Heretofore, in measuring viscosity, the fluid to be tested has been placed in a vessel and a rotor has been rotated in this fluid by a gear arrangement driven by a string carrying a weight. By the use of a counter which measures the number of revolutions of the rotor and a stop watch, the number of rotations per unit of time is determined. By suitable calculations, the viscosity of the fluid under test may be determined. It is evident that this method of measuring viscosity is rather complicated and requires constant adjustment of the apparatus while the measurement is being taken.

In accordance with this invention, the rotor is driven by asynchronous motor through a powertransferring mechanism which can be adjusted to vary the coupling between the rotor and the synchronous motor. When the motor and rotor are both rotated at predetermined rates, the energy consumed by the power-transferring device is proportional to the viscosity of the liquid or fluid under test.

It is an object of the invention to provide improved apparatus for measuring viscosity.

It is a further object to provide such apparatus in a compact, rugged formed wherein the parts are available at low cost.

Various other objects, advantages, and features of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawing, in which the figure is a front elevational view, partially in section, of the viscosity measuring apparatus of this invention.

Referring now to the drawing in detail, I have shown a vessel It containing a quantity of liquid I I of the fluid whose viscosity is to be measured. An inverted, cup-shaped rotor I2 is supported by a shaft I3 below the surface of the liquid I I, the shaft I3 being connected through a gear box and speed indicator I4 to a shaft I5 forming a part of a coupling device or power-transferring mechanism It. This latter device also includes a shaft I'I driven by a synchronous motor 18.

The coupling device It includes an outer shell or housing 26 having end caps 2| and 22 suitably secured thereto, together with an annular core 23 secured, as by brazing, to the end cap 22. The shell 20, end caps 2 I, 22 and core 23 are all formed from a suitable magnetic material and, if desired, they may be of laminated construction. The core 23 carries an annular coil 25 which is disposed within a suitable recess formed at the central outer region of the core.

3 Claims. (Cl. 73-59) The shaft has a reduced end portion. 2'I which is journalled in bearings 28 and 28 mounted in the respective end caps 23 and 22. A, cylindrical member 38 of magnetic material is mounted between shell 22 and core 23, this member being carried by an annuiar base SI fixed upon the shaft I5. The interior of the housing 20 is filled with small magnetic particles, such as iron powder, suspended in a suitable vehicle, such as lubricating oil or silicone liquids. A gasket 32 is mounted in end cap 2i to seal the region at which shaft it enters the housing, thereby to prevent the escape of fluid from the interior of the housing.

The coil 25 is supplied with electrical power by suitable conductors, not shown, which terminate at slip rings 3%, 35 fixed to the end cap These slip rings cooperate, respectively, with brushes 35 and 31, which are connected in circuit with an ammeter 38, a variable resistance a battery 40, and a switch ll in such fashion that the battery it supplies a current to the coil which may be regulated by resistance 39, connected in shunt with battery at, the resulting electrical current supplied to the coil being read upon the meter 38.

The construction of the coupling device I6 is such that the amount of coupling between shafts I5 and i l is proportional to the current supplied to coil 25 by battery it. That is, when the current delivered to the coil is of small magnitude, it is relatively easy for the shaft i5 to move relative to the shaft il whereas, when the current is increased, it is difficult for the shaft 55 to move relative to shaft I'i. Assuming that the motor I8 rotates at constant speed, and the load on shaft I3 is varied but shaft I3 is forced to rotate at a predetermined speed by adjustment of the mechanical coupling by the mechanism it, it will be evident that a heavy load upon shaft I5 will require a greater amount of power or torque and, hence, a greater consumption of electrical energy by the mechanism 55 in order to maintain shaft i5 at its predetermined speed of rotation. Conversely, a light load on shaft I5 requires that less energy be transferred to the shaft from motor I8 by the mechanism It and, hence, a lower consumption of electrical energy by the mechanism It. Thus, the energy supplied to the coupling device I8, as measured by meter 38, is proportional to the load on shaft is when this shaft and motor It are both rotated at constant predetermined speeds.

When the shaft I5 is coupled by gear box I4 and shaft [3 to the rotor I2, the load on shaft I5 is proportional to the viscosity of the liquid 3. II in container i0 and, hence, the reading of meter 38 is likewise proportional to the viscosity of the liquid. It will be apparent, therefore, that I have attained the objects of my invention in that the viscosity of any liquid may be quickly and accurately determined by rotating motor [8 at a predetermined speed and adjusting variable resistance 39-. until shaft I5 also rotates at a predetermined speed of rotation lower than that of motor it. Thereupon, the reading of meter 38 is proportional to the viscosity of the liquid under test.

It is to be understood that the described coupling device is merely illustrative and, that other types of coupling device, either electrical or mechanical, may be used without departing from the spirit and scope of the invention. It is a feature of my invention that the plasticity of the fluid may be determined, in addition to the viscosity. This is, accomplished by measu'ing the viscosity at various speeds of rotation of shaft.

I5, after which the viscosity is plotted against the speed of rotation of the shaft 15. This curve should be linear for a perfectviscosity characteristic, and departures from linearity are due to the plasticity of the fluid under test.

As will be evident to those skilled in the art, various modifications of this invention can be made, in the light of the foregoing disclosure, and discussion, without departing from the spirit or scope or" the disclosure or from the scope of the claims.

I claim:

1. Apparatus for measuring viscosity which comprises, in combination, .a rotor adapted to be immersed in a fluid whose viscosity is to be measured, a constant speed motor, a coupling mechanism to connect said rotor to said motor, speed indicating means connected to said rotor, said coupling mechanism being adjustable to vary the 4 a power transmitted from said motor to said rotor whereby the speed of said rotor can be maintained constant, and means to indicate the power transmitted by said coupling mechanism as a function of the viscosity of said fiuid.

2. The combination in accordance with claim 1 wherein said rotor is a member of inverted cupshaped configuration.

3. Apparatus for measuring viscosity which comprises, in combination, a rotor adapted to be immersed in a fluid whose viscosity is to be measured, a synchronous motor, .a pair of spaced relatively rotatable members connected, respectively, to said motor and said rotor, a liquid vehicle in the region between said members, said vehicle having magnetic particles dispersed therein, a coil carried by one of said members, a source of electrical current connected to said coil, speed indicating means connected to said rotor, means to vary the current supplied to said coil to vary the power transmitted from said motor to said rotor whereby the speed of said rotor can be maintained constant, and means to indicate the current supplied to said coil as a function of the viscosity of said fluid.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,689,69 Hagy Aug. 10, 193'! 2,305,531 Hurndall Dec. 15, 1942 2,336,991 Newton Oct. 5, 1943 2,354,923 lvicliamee Aug. 1, 1944 2,365,339 Green Dec. 19, 1944 2,416,385 Loukomsky et al. Oct. 29, 1946 2,484,761 Stock Oct. 11, 1949 OTHER REFERENCES National Bureau of Standards, Technical Report 1213, April 2, 1948. 

